Practical 2 : Sieving

Aim :

1. The test is performed to determine the percentage of different grain sizes contained within
    soil ( microcrystalline,MCC and lactose)

2. Sieving also one of the ways to break the agglomerates by mechanical-shaking forces and
    to identify the size of particles

3. The mechanical or sieve analysis is performed to determine the distribution of the
     coarser,large-sized particles

Introduction :

Mechanical sieving is a one of simple technique using shaking forces for separating particles of different sizes. A small sieve such as used for sifting lactose/MCC has very small holes. Coarse particles are separated or broken up by grinding against one-another and screen openings. Depending upon the types of particles to be separated, sieves with different types ( 45,150,300,425,500 micro) of holes are used. Sieves are also used to separate coarser particles and finer particles from origin.

Equipment :

1. Mechanical shaker

2. weighing boat

3. 100 g of lactose/MCC

4. Set of sieves

5. Cleaning brush

6. Balance

Procedure :

1. The 100 g of lactose is weighed

2. Make sure that all the sieves are clean and assemble them in the ascending order of sieve
    nest (45,150,300,425,500 micro)

3. The lactose is put in the top of sieve

4. The sieve stack is placed in the mechanical shaker and shake for 15 minutes

5. The stack is removed from the shaker and carefully weigh and record the weigh retain
     lactose within each sieve stack.

6. The procedure 1-5 is repeated with MCC

  

Result & Calculation

Weight of lactose + weighing boat = 102.7243 g

     Weight of weighing boat =     2.7277 g

        Finer lactose that collect on the pan of sieves =   30.3206 g

               Total the lactose that retain in the sieves set =   69.6794 g

Size of sieves      aperture	<45 mic	45 mic	46-150 mic	151-300 mic	301-425 mic	426-500 mic
Lactose	30.3206	48.1848	11.9408	2.9796	3.3976	3.1766

Question :

1.         What are the overall particles size analysis for lactose/MCC?

The overall particles size analysis are varies but the most dominant is   45 mic and followed by<45 mic , 46- 150 mic,301-425 mic,465-500 mic and lastly 151-300 mic.

2. What are the other method that can be used to identify the size of particle rather than sieving process ?

a) Microscope method

b)  Colter counter

c) Laser light scaterring method

d) sedimentation method

      3.    What are the importances of size particles analysis in formulation?

             Dimension of particulates are important in achieving optimum production of
             efficacious medicines especially in pharmaceutic phase

Discussion :

  

   Theotically, lactose particles having a volume average particle size of about 70 microns
      or less.than microcrystalline cellulose.

 

   

      From the  experiment shows that the particles size of lactose mostly approximately 50%

      (48.1848g ) is 45 micro and the and followed by less than 45 micro.This shows that the
      range size of lactose is <45 micro.The sieves is subjected to mechanical vibration as a   “driving forces” to sieve until less than 0.2% material passes in 5 minutes interval theoretically. But this experiment not too accurate because as we know that sieve

      stack comprises 5-6 sieves,so the nearer sieves ( at the bottom) to the mechanical shaker

  vibrate more rapidly than top so the distribution of particles is unreproducible for particle size analysis.

           

       Not only that the weight of origin lactose 100 g is disturbed because some of total

       Lactose stick on the sieves previously so the total not completely 100 g.

Sieving procedure are ineffective since too many error occur during experiment like loose of top closure cause many of lactose spill out from container.

Conclusion :

 Sieving process is extremely old technique,need hard work and cheap . It works in analysis the distribution of particles size in formulation to give an efficacious medicines.Then it help to ensure the pharmacokinetic phase

( absorbed,distribute,metabolism and elimination) works very well for theraupetic effect.

References :

1. http://www.pharma-excipients.com/micro-crystalline-cellulose.html

2. Note Particle size analysis by Dr Haliza Katas

3. http://www.google.com/patents/WO2005011594A2